RU2642926C2 - Method for knee joint anterior cruciate ligament reconstruction simulation - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: diameter of the resulting graft folded in half is measured. The same diameter of the tibial and femoral bone channels with their origin points in the knee joint cavity, exactly corresponding to the places of native anterior cruciate ligament attachment. A transplant is directed therein and fixed with pre-prepared cortical suture plates at the exit from the said channels.

EFFECT: method allows to reliably estimate the regenerative potential of grafts and the surrounding bone tissue during histological examination, to evaluate the quality of transplant engraftment.

3 cl, 5 dwg

Description

The invention relates to experimental medicine and can be used to reproduce a model of damage to the anterior cruciate ligament of the knee joint and its subsequent reconstruction in animals with the aim of improving the techniques for selecting, conducting and fixing transplants, as well as studying bioplastic processes in tendon transplants under standard conditions and when using different kind of biostimulants.

Despite the fact that at present the surgery of the anterior cruciate ligament (PCA) is at a high technical level, the terms for patients returning to work and sport after arthroscopic plastic surgery of the PCC have undergone not so significant changes and remain quite long. Therefore, the search for ways and means of accelerating the engraftment (integration) in the bone canals of tendon grafts used for PCS plastic surgery and their early structural restructuring - “ligamentation” will be crucial in the future. The solution to these problems will intensify and accelerate the process of rehabilitation after surgery. According to Ekdahl M. (Ekdahl M. Graft healing in anterior cruciate ligament reconstruction / M. Ekdahl, JH Wang, M. Ronga, FH Fu // Knee Surg Sports Traumatol Arthrosc. - 2008. - Vol. 16. - P. 935 -947) without the use of biotechnology, it is not possible to begin an aggressive rehabilitation of up to 12 weeks due to poor biological integration of the tendon graft.

For the justified and effective use of biological stimulants of plastic processes, as well as determining the optimal timing for evaluating their effectiveness, it is necessary to take into account the dynamics of morphological changes in the tendon graft after its installation, as well as in the area of its contact with the bone canal.

Since the direct evidence of the effectiveness of a particular biotechnology is the data of a histological study of biological samples, and their removal from patients, for obvious reasons, is extremely difficult, a convenient way to objectify the results of using biostimulants is to create an experimental animal model of reconstruction of PCS.

There is a method of creating an experimental model of PKS plastic (Roskov R.V. Plastic surgery of the anterior cruciate ligament of the knee joint with canned tendon homografts. Thesis ... Ph.D. / Roskov Rafael Viktorovich; LITO named after PP Vredena. - L., 1970. - 265 c.), where the author, to study the regeneration of ligaments of the knee joint, used a well reproducible experimental model of PCS plastic surgery in rabbits using various grafts, which is an indisputable advantage of this work. However, the tendon grafts used by the researcher and the methods of their preservation (common flexor of the toes prepared as an allograft, preserved by freezing, either in paraffin or in the RGDM solution in different series of experiments, as well as the same tendon as a pre-frozen autograft) are not used in humans . During the operations, the author also formed standard bone channels in the tibia and femur with a diameter of 2.5 mm, which hardly corresponded to the tight fit of the tendon to the bone wall in each case. To fix the tendon, its ends were carried out under the lateral ligaments with their transossal fixation with threads, which casts doubt on the quality of the graft tension. Given the above, to ensure the immobility of the graft in the bone canals, the author used gypsum immobilization of the operated limb for up to 30 days, which can give distorted histological results compared with the active (without immobilization) management of the postoperative period.

The closest in technical essence and purpose is the method (Bachy M, Sherifi I., Zadegan F. et al. Anterior cruciate ligament surgery in the rabbit. Journal of Orthopedic Surgery and Research 2013, 8:27), which also involves the creation of an experimental model PCB plastics in a rabbit. The authors rightly consider the rabbit to create the model the most economically viable animal, and the developed model is well reproducible and suitable for testing various biotechnologies based on it. Despite the authors' statement that the experimental model they created accurately copies the PCS plastic in humans, it has a number of significant drawbacks. First, the researchers used as a transplant only the allotomy of the long extensor of the fingers, which is not used in the treatment of PCS in humans. Secondly, this tendon was pulled into the bone channels in the form of a single bundle, while a person uses two- or four-beam transplants. Thirdly, when drilling bone channels, a drill with a diameter of 2 mm was always used, which makes it possible to doubt the exact correspondence of the diameter of the bone channel and graft in each case. Fourth, the authors did not indicate the anatomically accurate location of the bone canals corresponding to the attachment sites of the native PCS. Finally, the transplant was fixed by transossally fixing it with non-absorbable sutures at the exit of the tibial and femoral canals, which led to additional trauma to the bone and could not provide absolute immobility of the transplant in the absence of external immobilization. Based on the described shortcomings, this method cannot be considered optimal from the point of view of compliance with plastic surgery in the clinic, and accordingly, it is incorrect to conduct a study of biological processes on its basis in order to further extrapolate the data obtained with respect to patients.

The main objective of the invention is to create an experimental model that is as close as possible to the standard technique of autologous and alloplasty PCC in a clinic to study the regenerative potential of allo and autografts under standard conditions and under the influence of biostimulants on them to study the effectiveness of the latter.

The technical result of the invention consists in the possibility of the most reliable assessment of the regenerative potential of tendon grafts and their surrounding bone tissue during subsequent histological examination, as well as the quality of engraftment of tendon grafts after reconstruction of the PCB in the rabbit in order to optimize the treatment of patients with PCS ruptures.

The result of the invention is achieved in that grafts for the restoration of PKC in a rabbit are taken and prepared by methods accepted in clinical practice. So, for autoplasty of the anterior cruciate ligament in animals, as in humans, an autograft is used, prepared from a semi-tendon muscle previously taken from the operated extremity of the tendon. An allograft preliminarily taken from a limb of a relative, previously removed from the experiment, in the form of a flexor tendon of the foot and toes, is subjected to sterilization and preservation in a Belyakov's environment similar to human allograft. When drilling bone canals, strict compliance is made between the diameter of the drill and the previously measured diameter of the two-beam graft. Bone channels form anatomically, i.e. their starting points in the cavity of the knee joint exactly correspond to the places of the tibial and femoral attachment of the native anterior cruciate ligament. After the transplant is carried out into the bone canals, for its fixation at the exits from the tibial and femoral bone canals, specially prepared nortical suture titanium plates similar to the used EndoButton suture nortical fixation system in humans are used.

The drawings show:

FIG. 1 - View of the native anterior cruciate ligament of the rabbit knee joint (photo).

FIG. 2 - Highlighted tendon of the semitendinosus muscle of the rabbit (photo).

FIG. 3 - Prepared autograft (photo).

FIG. 4 - The transplant into the bone canals (photo).

FIG. 5 - Transplant fixation using a nortical titanium plate (photo).

To justify the method, an experimental study was carried out on twelve sexually mature Chinchilla rabbits weighing 2500-2800 grams from vivarium of the Federal State Budget Scientific Institution RNIITO named after P.P. Harmful ”in accordance with the rules adopted by the European Convention for the Protection of Vertebrate Animals Used for Experimental and Other Purposes - Council Directive 86/609 / EEC of 24 November 1986 on the approximation of laws, regulations and administrative provisions of the Member States regarding the protection of animals used for experimental and other scientific purposes (Official Journal L 358, 18/12/1986 P. 0001-0028) and the requirements of the "Rules for the use of experimental animals" (Order of the Ministry of Health of the USSR N 755 of 08/12/07 "On measures to further improve the forms of work using "experimental animals").

According to the study, twelve rabbits were divided into two groups (control and experimental), six individuals in each. Each of the groups, depending on the type of transplant used, was divided into two subgroups - “auto” and “hello” - three animals each. Rabbits of the control group were reconstructed with the standard design method, and rabbits of the experimental group - by the claimed method. The difference between the methods is the accuracy of the positioning of the femoral canal, the degree of correspondence of the diameter of the bone canals and the tendon graft and the method of its fixation.

The method is as follows.

Under intravenous anesthesia in the position of the rabbit on the back after treatment of the skin with an antiseptic (Klindesin-elite OP RED, Germany), a median skin incision of 7 cm is performed in the projection of the right knee joint. The aponeurosis and capsule of the joint are dissected from the lateral side. In the extension position of the rabbit’s hock limb, the patella is dislocated to the medial side, thereby providing a good visualization of the anterior part of the knee joint with a fatty body, intercondylar notch, transverse meniscus ligament and cruciate ligaments. Using a pointed scalpel, the fatty body in the anterior part of the knee joint and the native PKC are excised, and its remains at the attachment sites are removed using a bone spoon - in order to prepare the bed for subsequent conduct of a tendon graft (Fig. 1).

When performing an intervention, “autopodgroups” rabbits from the same operative approach bluntly isolate a semitendinosus muscle with a tendon. The tendon of the semitendinosus muscle is taken on a ligature and cut off from its attachment to the medial condyle of the tibia and muscle abdomen, the latter is sutured to the muscles of the inner thigh group (Fig. 2).

When performing operations with “allogroups” animals, allografts of the flexor of the foot and fingers are used as a graft, which are taken in advance from relatives, subjected to processing and sterilization by canning in Belyakov’s environment with control of sterility and compliance with the expiration date. During the operation, a pre-prepared allo-tendon is simply removed from the preservation solution in a sterile bag, followed by five minutes exposure in sterile saline.

After processing autologous tendons from the remnants of muscle tissue on the preparation base, the two-beam autograft is formed from the latter by folding the tendon in half with the Mersilene 2/0 ligature “traction” being inserted into the loop formed. The resulting transplant has a length of 20-25 mm, and a diameter of 2.0-2.5 mm. The graft diameter of the animals of the experimental group was measured by pulling the graft behind the ligature "traction" in the holes with a step of 0.5 mm in a standard metal measuring plate in series until an exact match between the diameter of the hole and the graft. The ends of the graft are stitched with non-absorbable Ethibond 2/0 filaments, which served as “piercing” ligatures. An allograft is similarly prepared (Fig. 3). The measurement of the diameter of the auto- and allografts to the control group rabbits was not performed.

From the base of the medial condyle of the tibia to the site of the native tibial attachment of the PCB (anatomically) “outside-inside” with a 1 mm drill, a bone channel is formed, which, after assessing the correctness of the entry and exit points, as well as its direction, is drilled with a drill corresponding in diameter to the thickness of the graft. The tibial canal in both groups is formed equally - anatomically - to prevent the so-called anterior impingement syndrome in the control group, the presence of which can lead to mechanical damage to the graft, which will directly affect the result of the experiment. However, if in the experimental group the diameter of the bone channel corresponds exactly to the diameter of the graft, then in the control group it is taken as an average value of 2.5 mm, since the standard technique does not imply that the diameter of the graft is exactly the same as the diameter of the bone channel.

By a similar technique - first with a thin drill, and then with a canal drilling with a thicker drill, a channel is formed in the femur from the inside out. In animals of the main group, the femoral canal is formed in such a way that the place of entry into it from the side of the joint cavity is chosen in exact accordance with the place of attachment of the native PCS. In the control group, the beginning of the femoral canal is arbitrary and placed at one point on the medial surface of the lateral condyle of the femur. The choice of the final diameter of the femoral canal is carried out in different groups according to the principle similar to that in the formation of the tibial canal.

To attach the PCD graft in rabbits of the experimental group, the technique of cortical fixation on titanium suture plates is used. One plate is placed at the outlet of the femoral and tibial canals, respectively. A graft pre-stitched with ligatures is tied to the plates in a state of tension. The graft does not lose tension until it completely grows into the wall of the bone canal. To exclude the plate from falling deep into the bone canal in the framework of this experiment, given that the diameter of the bone canal varies between 2-2.5 mm, titanium plates are made with dimensions 5 × 3 × 1 mm in length, width and thickness, respectively. Along the long axis of the titanium plate at an equal distance from its center, two holes of 1 mm diameter are formed by drilling to pass ligatures into them.

Using the “traction” ligature, an auto- or allograft is carried out into the bone channels (Fig. 4) and fixed on the external cortical layer of the femur by tying “stitching” ligatures on a suture titanium plate like an ordinary button (Fig. 5). The patella is set. After giving the knee joint a flexion position of 90 degrees, the graft in a tension state is fixed at the exit from the tibial canal by tying stitching ligatures on the same suture titanium plate.

In the control group, fixation is performed without the use of suture titanium plates - first, tangentially to the tibial and femoral canals, departing 3 mm from the edge of the hole, drill additional (one at a time) bone channels with a diameter of 1 mm. After that, the “piercing” ligatures and ligatures of the “thrust” are charged into a thin surgical needle, passed through the formed channels and tied up - they perform standard transossal fixation.

The wound is sutured in layers. The skin is treated with an antiseptic. Immobilization in both groups is not used.

Animals from both groups are removed from the experiment on the 15th day. Under the influence of a lethal dose of anesthetic, after switching off the consciousness in a rabbit, the instability tests of the knee joint are evaluated - the “front drawer” test and the Lachman test. In all animals of the experimental group in both subgroups, both of these tests were negative, indicating a lack of instability in the early postoperative period. In the control group in the “auto-subgroup” two animals also showed good results, but in one rabbit both instability tests were positive. In the control "allopodgroup" one rabbit showed a good result, the second - instability in one of the tests (test "front drawer"), the third - in both tests. Such results were due to unreliable fixation of the transplant, which in the absence of external immobilization led to its loosening.

After the postmortem opening of the cavities of the knee joints in all 6 rabbits of the experimental group, the PCS transplants were stretched and had no signs of damage. In 2 rabbits of the “auto-subgroup” of the control group, a similar picture was observed, in one, a significant weakening of the transplant tone was visualized with its superficial erosion, which appeared due to improper positioning of the femoral canal and the presence of increased friction on the upper lateral edge of the intercondylar notch of the femur. In one rabbit from the control "allopodgroup" the graft was stretched and had no signs of damage. The second graft was weakened, but also had no damage. And, finally, in the third rabbit, the PKC allograft was completely torn at the level of its entry into the femoral canal, which was a consequence of the mismatch between the diameter of the graft and the diameter of the bone canal.

Thus, the claimed method for modeling reconstruction of the anterior cruciate ligament of the knee joint is reliable, as close as possible to that in the clinic and will allow on its basis to improve the techniques for selecting, conducting and fixing transplants, as well as studying bioplastic processes in tendon grafts under standard conditions and when using various kinds of biostimulants.

Claims (3)

1. A method for simulating reconstruction of the anterior cruciate ligament of the knee joint, including the formation of bone channels in the tibia and femur of the rabbit, conducting a graft of the anterior cruciate ligament in them, followed by its fixation, characterized in that the graft is prepared using the methods adopted in clinical practice, then the diameter is measured the resulting transplant, folded in half, then the tibial and femoral bone channels with the points of their origin in the cavity are formed of the same diameter and the knee joint, exactly corresponding to the attachment points of the native anterior cruciate ligament, after which a graft is carried out in them and fixed with pre-prepared nortical suture plates at the outlet of the said channels. 2. The method according to p. 1, characterized in that the allograft is prepared from tendons of the flexor of the foot and toes of a congener. 3. The method according to p. 1, characterized in that the autograft is prepared from a tendon of a semi-tendon of a rabbit muscle.

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